English as the sole language for all future content

Context

ADR-070 (2026-07-10) made English the default language for the repository's existing content, migrated across 6 chantiers (root docs, public site, guidelines, .claude/, decisions, component code). All 6 chantiers completed 2026-07-14. Chantier 5 (decisions/) deliberately used a lightweight strategy for the 70 existing ADRs: a short English summary at the top, with the full French body preserved unaltered as the historical record — explicitly chosen over full retroactive translation, given the volume and the framing of ADRs as a dated historical log.

With the migration complete, the Design System Lead expressed a broader, permanent intent that goes beyond the one-time migration ADR-070 covered: Agentica should be adoptable by design system teams anywhere, not only French-speaking ones. This requires a standing language policy for content created from now on, not just a retroactive cleanup of what already existed — a decision ADR-070 did not make, since it was scoped to migrating existing content.

Decision

1. All new repository content is authored in English only, effective immediately — ADRs, guidelines, rules, instructions, skills, code comments, commit messages, everything. No French draft or French version is produced for new content.

2. Exception: the public website (site/) and its generated documentation stay bilingual FR/EN, English by default. This is the only part of the project where French continues to be actively maintained going forward — it is the direct-facing surface for the project's current French-speaking users, and the existing lang-fr/lang-en toggle mechanism makes the incremental cost of keeping it near-zero.

3. ADRs created before this decision (ADR-001 through ADR-070) are retroactively given a full English translation, superseding chantier 5's lightweight-summary strategy. Both the English and French versions live in the same source file, structured so the site can toggle between them using the same mechanism as the rest of the site (see point 5). This translation is tracked and executed as a separate, batched follow-up effort — it does not block this ADR from taking effect for new content.

4. ADRs created from this decision onward (ADR-071 and beyond) are English-only. No French section is required or maintained for them.

5. The website renders each ADR's language dynamically via the existing data-lang attribute and .lang-fr/.lang-en CSS toggle — the same mechanism already used across 1,249+ span pairs elsewhere on the site — rather than showing both languages sequentially on one scroll (chantier 5's current pattern) or generating separate per-language URLs per ADR. site/build.js's ADR rendering (loadADRs(), buildADR()) is updated to parse each ADR's English and French blocks separately and wrap them accordingly. This is a separate, tracked implementation task following this ADR.

Rationale

• A design system's credibility with international teams depends on being legible

without translation friction — English is the de facto standard for open-source design system tooling and documentation.

• Keeping the *site* bilingual (rather than dropping French everywhere) preserves

accessibility for the project's existing French-speaking users and stakeholders, at near-zero incremental cost since the toggle infrastructure already exists and is already exercised across the whole site.

• Splitting "future = English only" from "past = fully bilingual" avoids two costly

extremes: perpetually translating every future ADR into French forever, or abandoning the French readership of 70 already-written historical decisions overnight.

• Reusing the site's existing lang-toggle mechanism for ADR pages — instead of inventing

per-language URLs or a literal side-by-side markdown dump — keeps one i18n architecture for the whole site instead of two parallel ones to maintain.

Rejected alternatives